“Although Kanger’s greatest achievements were in pure logic he also made important contributions to philosophy by applying logical techniques within ethical theory, philosophy of law, philosophy of language and philosophy of science. His dissertation, Provability in Logic (1957), contains major contributions to two central areas of logic. By combining Gentzen’s sequent calculus with the model theory of Tarski, he obtains new and simplified proofs of central metalogical results like Gödel’s completeness theorem, Löwenheim-Skolem’s theorem and Gentzen’s Hauptsatz. He also develops a new semantic theory for various modal logics and connects it with sequent calculi for these logics. This work makes Kanger one of the founders of possible-worlds semantics” (Biographical Dictionary of Twentieth-Century Philosophers).
